1. Field of the Invention
This invention relates to a soda drink selling machine for producing soda drinks by dissolving syrup and CO.sub.2 gas into water. More specifically, this invention relates to a method of producing soda drinks by purifying local raw water at the site of providing the soda drink, and to a soda drink selling machine with a compact purified-water producing unit, so that the soda drink selling machine is enabled to be installed to places even where purified water suitable for drinks is unavailable.
2. Description of the Related Art
Since it is prerequisite that raw water under sufficient quality control can be obtained as water for a soda drink selling machine, it is hitherto common for a soda drink selling machine to use local raw water as water for dissolving various drinking ingredients. Thus, the conventional soda drink selling machine is not equipped with a water-purifying means.
In a place where purified water suitable for drinks is unavailable, disinfected water with chlorine is usually supplied as the minimum requirements. Raw water supplied under such unfavorable conditions may contain chlorine as described above, various kinds inorganic impurities, and in some cases, organic impurities. In this case, although the chlorinated water may be accepted as an ordinary drinking use, since the chlorine and other impurities may subtly affect the odor and taste as well as the stability of an amount of dissolved CO.sub.2 gas, it is not suitable for use in a soda drink selling machine. In case of worse conditions, local raw water is not even drinkable. In such places, in respect to matters of cost and time, it is actually impossible to treat all-purpose local raw water to make suitable enough to be used as purified water in a soda drink selling machine.
Meanwhile, a variety of methods and apparatuses are disclosed as a related art to the present invention. U.S. Pat. No. 5,086,951, discloses "portable post-mix beverage dispenser unit". However, in order to use this art, a source of purified water must be at close range. That is, a portable water tank filled with drinkable water must be equipped to the beverage dispenser, which necessitates the purified-water filled tank to be transported so as to be attached to the beverage dispenser. The beverage dispenser equips a refrigerator but solely for functioning as freeze storage or temperature adjustment of water. Consequently, such a dispenser is unable to be installed or operated in a place of poor raw water quality.
In U.S. Pat. No. 5,124,088, "Process and Apparatus for Rapidly Carbonating Water", a carbonating tank for use in a post-mix beverage dispenser is proposed. The sole feature of the art is that the carbonating tank is a pressure container that maintains a concentration of dissolved CO.sub.2 gas in water by injecting CO.sub.2 in a restricted manner under pressure. There are no special disclosures of any other features especially as for the restriction or new idea with respect to the quality of raw water. Therefore, such an apparatus is unable to be installed or operated in a place of unsuitable raw water quality.
Further, U.S. Pat. No. 5,353,958 discloses a carbonated beverage dispenser with a constant temperature mixing valve. This carbonated beverage dispenser includes a chiller, an ice maker, and a mixing valve to dissolve carbonic acid at the appropriate temperature so as to increase the concentration of carbonic acid and to maintain the concentration of carbonic acid after dissolution. This art solves a problem relating only to the concentration of carbonic acid and since the art uses municipal water, it does not take measures to cope with raw water of poor quality. Accordingly, this invention is also not suitable for operation at sites where the condition of the raw water is of a poor quality.
Furthermore, U.S. Pat. No. 5,464,124 discloses an apparatus for producing and dispensing post-mix beverage. The art is characterized in that raw water is cooled by utilizing water cooling function of the carbonator tank so as to provide both carbonated drinks and fresh water drinks. There are no special disclosures of any other features especially as for the quality of raw water. Therefore, such an apparatus is unable to be installed or operated in a place of unsuitable raw water quality.